Prior knowledge employs pre-stimulus alpha-band oscillations and persistent post-stimulus neural templates for conscious perception.

Prior knowledge has a profound impact on the way we perceive the world. However, it remains unclear how the prior knowledge is maintained in our brains and thereby influences the subsequent conscious perception. The Dalmatian dog illusion is a perfect tool to study prior knowledge, where the picture is initially perceived as noise. Once the prior knowledge was introduced, a Dalmatian dog could be consciously seen and the picture immediately became meaningful. Using pictures with hidden objects as standard stimuli and similar pictures without hidden objects as deviant stimuli, we investigated the neural representation of prior knowledge and its impact on conscious perception in an oddball paradigm using electroencephalogram (EEG) in both male and female human subjects. We found that the neural patterns between the pre-stimulus alpha-band oscillations and post-stimulus EEG activity were significantly more similar for the standard stimulus than for the deviant stimuli, after prior knowledge was provided. Furthermore, decoding analysis revealed that persistent neural templates were evoked after the introduction of prior knowledge, similar to that evoked in the early stages of visual processing. In conclusion, the current study suggests that prior knowledge employs alpha-band oscillations in a multivariate manner in the pre-stimulus period and induces specific persistent neural templates in the post-stimulus period, enabling the conscious perception of the hidden objects. Significance Statement The visual world we live in is not always optimal. In dark or noisy environments, prior knowledge can help us interpret imperfect sensory signals and enable us to consciously perceive hidden objects. However, we still know very little about how prior knowledge works at the neural level. Using the Dalmatian dog illusion and multivariate methods, we found that prior knowledge uses pre-stimulus alpha-band oscillations to carry information about the hidden object and exerts a persistent influence in the post-stimulus period by inducing specific neural templates. Our findings provide a window into the neural underpinnings of prior knowledge and offers new insights into the role of alpha-band oscillations and neural templates associated with conscious perception.